Information processing and storage in a cochlear stimulation system

ABSTRACT

Information can be stored in a cochlear stimulation system by determining an item of patient specific information, transferring the item of patient specific information to an implantable portion of the cochlear stimulation system, and permanently storing the item of patient specific information in the implantable portion of the cochlear stimulation system. The item of patient specific information can comprise a parameter for use in generating a stimulation current. The implantable portion of the cochlear stimulation system also can be configured to permanently store one or more items of patient specific information in an alterable fashion. Further, an item of patient specific information can be retrieved from the implantable portion of the cochlear stimulation system. Additionally, an item of non-patient specific information for use in processing a received acoustic signal can be determined and permanently stored in an external portion of the cochlear stimulation system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application of U.S. patent application Ser. No.11/418,847, filed May 5, 2006, now U.S. Pat. No. 8,818,517, which isincorporated by reference, and to which priority is claimed.

BACKGROUND OF THE INVENTION

The present disclosure relates to implantable neurostimulator devicesand systems, for example, cochlear stimulation systems, and tostrategies for storing parameters employed in conjunction with suchsystems.

Prior to the past several decades, restoring hearing to the deaf wasgenerally believed to be impossible. More recently, however, scientistshave had increasing success in restoring normal hearing in subjectsaffected by substantial hearing loss. In some cases, hearing loss can beovercome through electrical stimulation. For example, electrical signalscan be applied to the auditory nerve, bypassing damaged cochlear haircells that may be disrupting hearing. Initial attempts to restorehearing using this type of technique were not very successful, becausesome patients were still unable to understand speech. Over time,however, the auditory sensations elicited by electrical stimulationgradually came closer to approximating normal speech. Electricalstimulation of the auditory nerve can be implemented through aprosthetic device, commonly referred to as a cochlear implant, which issurgically implanted into a subject affected by hearing loss.

Cochlear stimulation systems, such as the systems described in U.S. Pat.Nos. 5,938,691 and 6,219,580, each of which is incorporated herein byreference, produce sensations of sound in patients affected by hearingloss through direct stimulation of the ganglia of the auditory nervecells. Cochlear stimulation systems are generally comprised of severalcomponents, including an electrode array that incorporates one or moreelectrode pairs, an implantable cochlear stimulator, an externallywearable speech processor (or signal processor) with one or moremicrophones, and a communication path that couples the external speechprocessor and the implantable cochlear stimulator through the skin, suchas a radio frequency link. The external portion of the communicationpathway can be incorporated into a headpiece that can be affixed andaligned with the implantable cochlear stimulator, such as through theuse of one or more magnets. Alternatively, the external portion of thecommunication pathway can be integrated into the speech processor, whichcan be affixed adjacent to the pinna in proximity to the implantablecochlear stimulator.

The acoustic signals received by the one or more microphones included inthe cochlear stimulation system are transformed into sound data by thespeech processor. The sound data can then be transferred to theimplantable cochlear stimulator, such as by transmission over thecommunication pathway. Once received in the implantable cochlearstimulator, the sound data can be used to selectively generate theelectrical stimuli that are directed to one or more cochlea stimulatingchannels, each of which is associated with one or more electrodes orelectrode pairs included within the electrode array.

Within the cochlea, there are two main cues that convey “pitch”(frequency) information to the listener. They are (1) the place orlocation of stimulation along the length of the cochlear duct and (2)the temporal structure of the stimulating waveform. Specific frequenciesof sound are detected by specific portions of the cochlea, such thateach frequency is mapped to a particular location along the cochlea.Generally, from low to high, sound frequencies are mapped from theapical to the basilar direction. Accordingly, the electrode array can befitted to a patient to arrive at a mapping scheme such that electrodesnear the base of the cochlea are stimulated with high frequency signals,while electrodes near the apex are stimulated with low frequencysignals. Thus, the stimulation signals provided to the electrodes modelthe received acoustic signal associated with a particular frequencyband.

Several different strategies have been developed for processing detectedacoustic signals and transforming them into electrical stimuli that canbe applied to the cochlea. These strategies, often referred to as speechprocessing strategies, define a pattern of electrical waveforms that canbe applied as controlled electrical currents to the one or more cochleastimulating channels associated with the electrode array. Speechprocessing strategies can be broadly classified as: (1) sequential ornon-sequential pulsitile stimulation, in which only one electrodereceives an electrical pulse at a time; (2) simultaneous pulsitilestimulation, in which substantially all of the electrodes receiveelectrical pulses at the same time, approximating an analog signal; or(3) partially simultaneous pulsitile stimulation, in which only a selectgrouping of electrodes receive electrical pulses at the same time andthe electrical pulses are received in accordance with a predefinedpattern.

It also is possible to further divided these strategies based on thewaveform of the electrical stimuli, i.e., whether the electrical stimuliis an analog waveform or a biphasic (or multiphasic) waveform.Generally, analog waveforms represent filtered versions of a continuousacoustic signal, such as the signal received by a microphone. Analogwaveforms are typically reconstructed by the generation of continuous,short, monophasic pulses or samples. The rate at which the samples aretaken from a continuous acoustic signal must be high enough to permitthe accurate reconstruction of the temporal details of the continuousacoustic signal. If an analog signal is not sampled at a sufficientlyhigh rate, artifacts may result. Biphasic (or multiphasic) pulses,commonly referred to as pulsitile waveforms, typically include a singlecycle of a square wave in which current flows in one direction at aparticular magnitude and for a particular time, followed by a currentflow in the opposite direction at a similar magnitude and for a similarperiod of time.

There are numerous other stimulation patterns known in the art that maybe formulated. One simulation pattern may prove more effective for aparticular patient than any other stimulation pattern, since eachpatient may respond differently to a particular speech processingstrategy. The complex biophysical phenomenon associated with theelectrical stimulation of neurons and psychophysical phenomena regardingthe interpretation of neural activity by the auditory nervous systemsuggest that the quality and intelligibility of speech precepts evokedby a cochlear stimulation system may be improved in a given patient bymore specific manipulations of the electrical stimuli tailored to thatpatient. Stimulation strategies are described in further detail in U.S.patent application Ser. No. 11/226,777, which is incorporated herein byreference. Identifying which of the available speech processing andstimulation strategies is most beneficial for a given patient iscommonly performed at the fitting stage.

A specialist, such as an audiologist, generally customizes or “fits” anewly provided cochlear stimulation system to a patient. In fitting thecochlear stimulation system, the specialist selects the modes andmethods of operation that will be used by the system to help the patientperceive sound. The modes and methods include information defining thegeneral processing characteristics, such as parameters utilized by thespeech processor. Additionally, the modes and methods includepatient-specific information, such as stimulation parameters andsettings. Although the specialist can exercise a substantial amount ofcontrol and discretion in selecting the modes and methods of operation,the specialist typically employs a fitting system to properly customizethe cochlear stimulation system to meet the individual needs of apatient. Fitting systems are described in further detail in U.S. Pat.Nos. 5,626,629 and 6,289,247, both of which are incorporated herein byreference.

Once they have been determined, the modes and methods of operation canbe stored in the cochlear stimulation system for use in configuring thedevice each time it is initialized, which generally occurs whenever theexternal portion of the unit is powered off or disconnected from thepatient. During initialization, one or more items of information can betransmitted between the speech processor portion and the implantablecochlear stimulator. In the implantable cochlear stimulator, informationcan be stored in a random access memory for use during operation. Forexample, a speech processor can be configured to detect the presence ofan implantable cochlear stimulator and, upon such detection, communicatewith the implantable cochlear stimulator to configure the cochlearstimulation system for operation. Further, the speech processor caninclude one or more user controls, which can be used to configure theimplantable cochlear stimulator. Once configured, the implantablecochlear stimulator can use the patient specific parameters to generatethe electrical stimuli that are applied to one or more cochleastimulating channels. When configured to use one or more parametersstored in a volatile memory, an implantable cochlear stimulator can beperiodically monitored during operation. Alternatively, the implantablecochlear stimulator can be configured to notify the speech processor ofany change in configuration.

SUMMARY OF THE INVENTION

The present inventor recognized the need to permanently store patientspecific information, such as personalized configuration settings andindividual stimulation parameters, within the internal portion of acochlear stimulation system to reduce the amount of informationtransmitted to the internal portion, particularly during initialization.The present inventor also recognized the need to permanently storepatient specific information within the internal portion of a cochlearstimulation system to permit recovery of the patient specificinformation without reference to an external storage device. Further,the need to permanently store non-patient specific information, such asone or more general parameter associated with a speech processingstrategy, within the external portion of a cochlear stimulation systemis recognized.

The present inventor also recognized that, although patient specificinformation and non-patient specific information is permanently stored,at least a portion of the patient specific information and non-patientspecific information should be stored in a manner that also will allowit to be purposely altered, such as through a reprogramming operation.Additionally, the need to perform non-patient specific speech processingoperations within the external portion of a cochlear stimulation systemand patient specific speech processing operations within the internalportion of a cochlear stimulation system is also recognized. Further,the present inventor recognized the need to permit reprogramming ofnon-patient specific information, such as speech processing parameters,without necessitating the reprogramming of patient specific information.Accordingly, the techniques and apparatus described here implementalgorithms for permanently storing patient specific information in aninternal portion of a cochlear stimulation system, permanently storingnon-patient specific information within an external portion of acochlear implant system, and/or for performing speech processingoperations within a corresponding portion of a cochlear stimulationsystem.

In general, in one aspect, the techniques can be implemented to includedetermining an item of patient specific information, transferring theitem of patient specific information to an implantable portion of thecochlear stimulation system, and permanently storing the item of patientspecific information in the implantable portion of the cochlearstimulation system.

The techniques also can be implemented such that the item of patientspecific information comprises a parameter for use in generating astimulation current. The techniques further can be implemented such thatthe implantable portion of the cochlear stimulation system is configuredto permanently store one or more items of patient specific informationin an alterable fashion. Additionally, the techniques can be implementedto include initializing the implantable portion of the cochlearstimulation system using one or more of the permanently stored items ofpatient specific information.

The techniques also can be implemented to include determining an item ofnon-patient specific information for use in processing a receivedacoustic signal and permanently storing the item of non-patient specificinformation in an external portion of the cochlear stimulation system,wherein the external portion comprises a speech processor. Further, thetechniques can be implemented to include determining a substitute itemof non-patient specific information, permanently storing the substituteitem of non-patient specific information in the speech processor inplace of the item of non-patient specific information, retaining the oneor more items of patient specific information permanently stored in theimplantable portion of the cochlear stimulation system, and generating astimulation current using the substitute item of non-patient specificinformation and the one or more items of patient specific information.

The techniques also can be implemented to include replacing the speechprocessor with a substitute speech processor, retaining the one or moreitems of patient specific information permanently stored in theimplantable portion of the cochlear stimulation system, and operatingthe cochlear stimulation system using the substitute speech processor.The techniques further can be implemented to include retrieving the itemof patient specific information from the implantable portion of thecochlear stimulation system. Additionally, the techniques can beimplemented to include associating a write protection with the item ofpatient specific information permanently stored in the implantableportion of the cochlear stimulation system. Further, the techniques canbe implemented such that the associated write protection is reversible.

The techniques also can be implemented to include determining asubstitute item of patient specific information, transferring thesubstitute item of patient specific information to the implantableportion of the cochlear stimulation system, and permanently storing thesubstitute item of patient specific information in the implantableportion of the cochlear stimulation system in place of the item ofpatient specific information.

In general, in another aspect, the techniques can be implemented toinclude an implantable portion comprising circuitry configured toreceive an item of patient specific information and an internal memoryin the implantable portion configured to permanently store the receiveditem of patient specific information, wherein the internal memory iscapable of storing one or more items of patient specific information.

The techniques also can be implemented such that the internal memorycomprises one of an EEPROM, a flash EEPROM, an FRAM, and an embeddedprogrammable non-volatile memory. Further, the techniques can beimplemented to include processor electronics in the implantable portionconfigured to protect at least a portion of the internal memory fromalteration. Additionally, the techniques can be implemented to includeprocessor electronics in the implantable portion configured toinitialize the implantable portion using one or more items of storedpatient specific information.

The techniques also can be implemented to include processor electronicsin the implantable portion configured to ‘communicate one or more itemsof stored patient specific information to an external device. Further,the techniques can be implemented to include an external portioncomprising circuitry configured to receive an item of non-patientspecific information and an external memory in the external portionconfigured to permanently store the received item of non-patientspecific information, wherein the external memory is capable of storingone or more items of non-patient specific information. Additionally, thetechniques can be implemented to include processor electronics in theexternal portion configured to communicate sound data to the implantableportion, circuitry in the implantable portion configured to receive thesound data; and processor electronics in the implantable portionconfigured to generate a stimulation current using the sound data andone or more items of patient specific information.

In general, in another aspect, the techniques can be implemented toinclude initializing an implantable portion of the cochlear stimulationsystem using one or more items of patient specific information, whereinthe patient specific information is permanently stored in theimplantable portion and initializing an external portion of the cochlearstimulation system using one or more items of non-patient specificinformation, wherein the non-patient specific information is permanentlystored in the external portion. The techniques also can be implementedto include communicating control data from the external portion to theimplantable portion, wherein the control data defines a status of one ormore user controls.

The techniques described in this document may be implemented to realizeone or more of the following advantages. For example, the techniques canbe implemented to permit storing patient specific information in aninternal portion of a cochlear stimulation system. Further, thetechniques can be implemented to include recovering patient specificinformation from the internal portion of a cochlear stimulation system.The techniques also can be implemented to permit storing non-patientspecific information in an external portion of a cochlear stimulationsystem. The techniques further can be implemented such that only sounddata is transmitted from the speech processor to the implantablecochlear stimulator, thereby reducing the amount of information that istransmitted from the external portion to the internal portion of thecochlear stimulation system. Additionally, the techniques can beimplemented to reduce the frequency of or to eliminate altogether theperiodic validation of patient specific information stored in aninternal portion, thereby reducing the complexity of the communicationlink between the external portion and the internal portion of a cochlearstimulation system.

The techniques also can be implemented such that the cochlearstimulation portion can be configured as soon as the cochlearstimulation system is initialized, without having to first receiveinformation, such as parameters, from the speech processor portion.Further, the techniques can be implemented to permit replacing theexternal portion of the cochlear stimulation system, including thespeech processor, without replacing the internal portion of the cochlearstimulation system or requiring the patient to undergo a new fittingprocedure. Additionally, the techniques can be implemented to includereprogramming the speech processor, such as with a new speech processingstrategy, without requiring the patient to undergo a new fittingprocedure. Also, the techniques can be implemented to permit thesubstitution of an existing external speech processor with an alternateexternal speech processor without first programming the alternateexternal speech processor with patient specific information and withoutrequiring the patient to undergo a new fitting procedure.

These general and specific techniques can be implemented using anapparatus, a method, a system, or any combination of an apparatus,methods, and systems. The details of one or more implementations are setforth in the accompanying drawings and the description below. Furtherfeatures, aspects, and advantages will become apparent from thedescription, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a cochlear stimulation system.

FIGS. 2A and 2B depict a behind-the-ear prosthetic device for use in acochlear stimulation system.

FIG. 3 is a flowchart that describes establishing one or more patientspecific parameters.

FIG. 4 is a block diagram of a portion of an implantable cochlearstimulator.

FIG. 5 is a flowchart that describes the operation of a cochlearstimulation system.

FIG. 6 is a flowchart that describes the initialization of a cochlearstimulation system.

FIG. 7 is a flowchart that describes storing patient specificinformation in an implantable portion of a cochlear stimulation system.

Like reference symbols indicate like elements throughout thespecification and drawings.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 presents a cochlear stimulation system 10 that includes a speechprocessor portion 12 and a cochlear stimulation portion 20. The speechprocessor portion 12 includes one or more microphones 14 and a speechprocessor 18. The speech processor portion 12 can be worn, placed, orattached externally to a patient. For example, the speech processorportion 12 can be incorporated into a housing that can be worn, such asthe behind-the-ear prosthetic device 200 depicted in FIG. 2A or thebehind-the-ear prosthetic device 210 depicted in FIG. 2B. The externalportion of the communication link 26 that couples the speech processorportion 12 and the cochlear stimulation portion 20 can be included inthe housing, such as in the behind-the-ear prosthetic device 200depicted in FIG. 2A. Alternatively, as shown in FIG. 2B, a communicationdevice 230 that comprises the external portion of the communication link26 can be coupled to the behind-the-ear prosthetic device 210 through aninterface 220. The interface 220 can be wired or wireless.

Further, the one or more microphones 14 can be included in the housingincorporating the speech processor 12 or can be situated within theouter ear, the ear canal, or the middle ear of the patient. The one ormore microphones 14 can be connected directly to the speech processor 18using a physically coupled communication link 16, such as one or morewires. Alternatively, the communication link 16 can be wireless and theone or more microphones 14 can be coupled to the speech processor 18through an appropriate communication link 16, such as a radio frequencylink or any other wireless data link capable of communicating sensedacoustic signals to the speech processor 18. In another implementation,a channel, such as a sound tube, can be located within the outer ear,the ear canal, or the middle ear of the patient in order to conveysensed acoustic information to the one or more microphones 14 includedin the speech processor portion 12.

The cochlear stimulation portion 20 can include an implantable cochlearstimulator 22 and an electrode array 24, which combine to form one ormore cochlea stimulating channels. Each of the cochlea stimulatingchannels is typically associated with an individual electrode, a pair ofelectrodes, or a grouping of electrodes located within or on theelectrode array 24. The electrode array 24 is adapted to be implantedwithin the cochlea of a patient and includes a plurality of electrodes,e.g., sixteen or thirty-two electrodes, spaced along its length that arecoupled to and can be selectively stimulated by the implantable cochlearstimulator 22. Electronic circuitry within the implantable cochlearstimulator 22 produces a specified stimulation current that is to beapplied to selected electrodes included within the electrode array 24 inaccordance with one or more items of stimulation information, e.g.,processed sound data, received from the speech processor 18. Theelectrode array 24 may be substantially as shown and described in U.S.Pat. Nos. 4,819,647 and 6,129,753, each of which is incorporated hereinby reference. Alternatively, the electrode array 24 can be any otherelectrode array known in the art.

The speech processor 18 and the implantable cochlear stimulator 22 canbe electronically coupled through a suitable communication link 26. Inan implementation, the communication link 26 can comprise atranscutaneous (through the skin) link that allows power, control data,and processed sound data to be transmitted from the speech processor 18to the implantable cochlear stimulator 22. In another implementation,the implantable cochlear stimulator 22 also can be configured totransmit information, such as parameters and status signals, to thespeech processor 18 over the communication link 26. In order tofacilitate bidirectional communication between the speech processor 18and the implantable cochlear stimulator 22, the communication link 26can include more than one channel. Additionally, interference betweenthe channels can be reduced or eliminated through the use of differenttransmission techniques. For example, information can be transmitted ona first channel using an amplitude-modulated carrier and information canbe transmitted on a second channel using a frequency-modulated carrier.

The communication link 26 can be realized though use of an implantedantenna coil, such as an antenna coil included in the implantablecochlear stimulator 22, and an external antenna coil included in orcoupled to the speech processor portion 12. The external antenna coilcan be positioned so that it is aligned with the implanted antenna coil,allowing the coils to be inductively coupled to one another and therebypermitting power and information, e.g., stimulation signals and controldata, to be transmitted from the speech processor 18 to the implantablecochlear stimulator 22. The inductively coupled coils also can be usedto transmit information from the implantable cochlear stimulator 22 tothe speech processor 18.

In multi-channel cochlear stimulation systems, complex stimulationpatterns involving one or more sites along the cochlea can be producedin order to more accurately evoke responses representative of thedifferent pitches that are normally present in sound. These complexstimulation patterns can be generated with respect to a plurality offactors, including frequency, pulse amplitude, and pulse width.Additionally, stimulation may be delivered to the patient in asimultaneous stimulation pattern, in which two or more electrode pairsproduce stimulation at substantially the same time, or a sequentialstimulation pattern, in which only one electrode pair producesstimulation at a given time. Because cochlear stimulation has becomeincreasingly sophisticated, a cochlear stimulation system, or cochlearimplant, is typically customized in one or more fitting sessions toprovide individualized stimulation to the patient.

When a cochlear stimulation system, such as the cochlear stimulationsystem 10 depicted in FIG. 1, is first provided to a patient, anaudiologist or other such specialist initially selects the modes andmethods of operation that characterize the system, such as the selectionof an appropriate speech processing strategy. The specialist selects themodes and methods of operation such that the cochlear stimulation system10 will be able to best perform its intended function of helping therecipient to sense sound. Upon the selection of a speech processingstrategy, the information defining the selected speech processingstrategy, including operating parameters such as spatial and temporalstimulation parameters, can be customized to the needs of the patient.The operating parameters can include the duration and shape of thestimulation waveform, location information (e.g., the identification ofthe specific electrode or electrode grouping that is to receive thestimulation current), and timing information (e.g., when the stimulationcurrent is to be applied to the electrode or electrode grouping).Because they are customized to meet the needs of an individual patient,the operating parameters represent a type of patient specificinformation.

FIG. 3 presents a flowchart describing a fitting session 300, duringwhich operating parameters comprising patient specific information areselected. During the fitting session 300, thresholds and thresholdvalues associated with one or more psychophysically-determinedpseudo-comfort levels can be measured and selected. In animplementation, a cochlear stimulation channel associated with thecochlear stimulation system can be identified 310 and one or more levelsassociated with the identified channel can be set. For example, aminimum threshold T can be established 320 for the identified cochlearstimulation channel. The T-level represents the minimum stimulationcurrent, which, when applied to an electrode associated with thecochlear stimulation channel produces a sensed perception of sound inthe patient at least 50 percent of the time. It also is possible toestablish a comfort-level threshold M 330 that corresponds to theidentified cochlear stimulation channel. The M-level is a comfort levelthat represents a stimulation current, which, when applied to anelectrode associated with the cochlear stimulation channel produces asensed perception of sound in the patient that is moderately loud, butdoes not produce discomfort. Therefore, the T- and M-levels associatedwith one or more channels can be used by a fitting system to properlymap sensed sounds to electrical stimuli (e.g., current levels) that canbe perceived by the patient.

An upper stimulus level (USL) that corresponds to the identifiedcochlear stimulation channel also can be established 340. The USLrepresents the maximum stimulation current that can be applied to theone or more electrodes associated with the identified cochlearstimulation channel, which will produce a sensed perception of sound inthe patient that can be tolerated. Since the M-level represents acomfortable stimulation current, the USL is typically selected such thatit exceeds the M-level but does not exceed the maximum comfort level ofthe patient. In an implementation, the USL can be set at a level thatexceeds the M-level by an arbitrary amount, such as 10 μA.Alternatively, the USL can be independently measured and establishedduring the fitting session 300 using the response to feedback providedby the patient. After one or more of the levels associated with theidentified cochlear stimulation channel have been established, it can bedetermined whether any cochlear stimulation channels remain for whichone or more levels are to be established 350. If such an additionalcochlear stimulation channel remains, the additional channel can beidentified 310. Otherwise, a Global USL parameter can be established360.

A Global USL parameter can be used to offset the individual USLparameter values corresponding to the one or more cochlear stimulationchannels of the cochlear stimulation system. The Global USL parametercan be used to provide lateral movement of the input-output amplitudecurve while maintaining the relative relationships between the values,wherein the input is the amplitude data of the sensed acoustic signaland the output is the amplitude of the electrical stimuli. Additionally,one or more spatial stimulation parameters and temporal stimulationparameters associated with a speech processing strategy also can beestablished during a fitting session 300. In another implementation, anycombination of the Global USL parameter, spatial stimulation parameters,temporal stimulation parameters, and the T-level, M-level, and USLparameters associated with the one or more cochlear stimulation channelsincluded in the cochlear stimulation system can be set or reset during afitting session 300.

When one or more items of patient specific information have beenestablished, such as the patient specific parameters associated with theone or more cochlear stimulation channels, the patient specificinformation can be transmitted to the cochlear stimulation portion 20.For example, the patient specific information can be transmittedtranscutaneously over the communication link 26. Once received in thecochlear stimulation portion 20, the patient specific information can bepermanently stored, such that the information is preserved even in theabsence of power. In this manner, the stored patient specificinformation will be permanently associated with the patient.

In an implementation, the stored patient specific information also canbe transmitted from the cochlear stimulation portion 20, e.g. over thecommunication link 26, to an external device, such as the speechprocessor portion 12 or a separate programming device. Retrieval of thestored patient specific information can be performed to identify thestored values, such as for verification purposes after a fittingsession. If a discrepancy is detected, the storing operation can berepeated for one or more items of patient specific information to ensurethat the correct information is stored in the cochlear stimulationportion 20. Other patient specific information can be transmitted andstored in the same manner at any point in time.

FIG. 4 presents a block diagram of an implementation of the implantablecochlear stimulator 22, through which acoustic-to-electrical amplitudemapping techniques can be implemented. The implantable cochlearstimulator 22 can include a frame sequencer 400 that is coupled to oneor more channel sequencers 410 (one shown for illustration). Further,each of the one or more channel sequencers 410 can include anon-volatile memory 420, in which one or more items of patient specificinformation, such as individualized parameters, can be stored.

Additionally, at least a portion of the patient specific informationstored in the non-volatile memory 420 can be protected againstalteration, such as unintentional deletion or modification. For example,the non-volatile memory 420 can be organized to include one or moreaddressable locations, e.g. bytes, blocks, or pages. A write protectionor other such access control mechanism can be associated with one ormore of the locations of the non-volatile memory 420, which when enabledprevents the associated data from being altered. Alternatively, theability to alter stored information can be controlled through passwordprotection or authentication. Further, the write protection associatedwith a specific memory location can be implemented as a reversibleprotection, such as a reversible flag, or as an irreversible protection,such as a fuse or a flag that designates the location as one-timeprogrammable. Additionally, the nonvolatile memory 420 can beimplemented to include any combination of reversible and irreversiblewrite protection.

Because patient specific information can be permanently stored in theimplantable cochlear stimulator 22, validation of the patient specificinformation during operation can be eliminated or the frequency of suchvalidation can be reduced. Therefore, the communication link 26 betweenthe speech processor portion 12 and the cochlear stimulation portion 20can be simplified. Still, the patient specific information also can bestored in a manner such that any of the one or more items of patientspecific information, such as a parameter, can be individually read fromthe non-volatile memory 420 and communicated to an external device.

In another implementation, two or more items of patient specificinformation can be stored in a single addressable location of thenon-volatile memory 420 to efficiently utilize the available storagecapacity. The non-volatile memory 420 can be implemented using anynon-volatile memory known in the art, including an electrically-erasableprogrammable read-only memory (EEPROM), a flash EEPROM, ferroelectricrandom access memory (FRAM), and an embedded programmable non-volatilememory.

The implantable cochlear stimulator 22 also can include a volatilememory 430, which can be configured to store information while theimplantable cochlear stimulator 22 is powered. For example, one or moreitems of patient specification information stored in the non-volatilememory 420 can be loaded into the volatile memory 430 for use duringoperation. Further, control data and processed sound data received fromthe speech processor 18 also can be stored in the volatile memory 430.The volatile memory 430 can be implemented using any volatile memoryknown in the art, including static random access memory (SRAM) anddynamic random access memory (DRAM).

With respect to FIG. 1, one or more non-patient specific parametersgenerally utilized by a speech processing strategy can be associatedwith the speech processor portion 12. As discussed above, speechprocessing parameters can be determined as part of the design of aspeech processor, or established during the development or revision of aspeech processing strategy. During operation of the cochlear stimulationsystem 10, one or more speech processing parameters can be used toprocess acoustic signals received by the one or more microphones 14. Toensure that it is readily accessible, the non-patient specificinformation can be permanently stored in the speech processor portion12, such as in a non-volatile memory 28 included in the speech processor18. In another implementation, the non-volatile memory 28 can beincluded in a different section of the speech processor portion 12,separate from the speech processor 18. In such an implementation, thenon-volatile memory 28 can be coupled to the speech processor 18, suchas by a bus or other communication pathway.

As with the implantable cochlear stimulator 22, the non-volatile memory28 included in the speech processor 18 can be implemented using anynon-volatile memory known in the art, including an electrically-erasableprogrammable read-only memory (EEPROM), a flash EEPROM, a ferroelectricrandom access memory (FRAM), an embedded programmable non-volatilememory, a programmable read-only memory (PROM), or any other such ROM.In an implementation using an alterable memory, one or more items ofnon-patient specific information stored in the non-volatile memory 28 ofthe speech processor portion 12 can be reprogrammed. Because thenon-patient specific information relates only to a general speechprocessing strategy, and not to patient specific stimulation patterns,the non-patient specific information can be reprogrammed withoutreference to the patient specific information stored in the non-volatilememory 420 of the implantable cochlear stimulator 22.

It also is possible to replace the speech processor 18 included in theexisting speech processor portion 12 with a compatible speech processorwithout requiring the patient to undergo an additional fittingprocedure. If the speech processor portion 12 is contained within asingle device, such a replacement may require exchanging the entirespeech processor portion 12. Alternatively, the speech processor portion12 can be configured to permit separately replacing the speech processor18. Further, the compatible speech processor can be configured toprocess speech differently from the speech processor 18, such as byusing a different speech processing strategy or through the use ofdifferent components. For example, the cochlear stimulation system 10can be upgraded by replacing the existing speech processor 18 with acompatible speech processor that is configured to use an improved speechprocessing strategy. Alternatively, the cochlear stimulation system 10can be upgraded by replacing the existing speech processor portion 12with a compatible speech processor portion.

FIG. 5 presents a flowchart describing the operation of the cochlearstimulation system 10. During operation of the cochlear stimulationsystem 10, the one or more microphones 14 in the speech processorportion 12 can sense acoustic signals and can convert the sensedacoustic signals to corresponding electrical signals (510). Theelectrical signals produced by the one or more microphones 14 areprovided to the to the speech processor 18 over an appropriatecommunication link 16, such as a circuit or wireless communication path(520). The speech processor 18 can process the received electricalsignals to extract amplitude data associated with the converted acousticsignals (530). For example, the speech processor 18 can include aconventional audio front end that features automatic gain control and ananalog-to-digital converter for transforming the received analog signalinto digital samples that represent amplitude data. The speech processor18 also can include one or more filters, e.g. band pass filters. Onceamplitude data has been extracted from the received electrical signals,the amplitude data can be further processed in accordance with a generalspeech processing algorithm (540), such as an algorithm that performsoperations such as filtering and noise cancellation. For example, thespeech processor 18 can process the received electrical signals inaccordance with one or more of the non-patient specific parametersstored in the non-volatile memory 28.

As a result of performing its portion of the signal processingoperation, the speech processor 18 produces sound data in the form ofone or more electrical signals that can be transmitted over thecommunication link 26 to the cochlear stimulation portion 20 (550). Inthe cochlear stimulation portion 20, the implantable cochlear stimulator22 receives the transmitted sound data. The implantable cochlearstimulator 22 can then further process the received sound data inaccordance with one or more items of patient specific information (560),such as those stored in the non-volatile memory 420.

For example, the received sound data can be processed in the implantablecochlear stimulator 22 to define the shape and duration of a stimulationwaveform with respect to one or more temporal stimulation parameters andspatial stimulation parameters stored in the non-volatile memory 420.Additionally, the amplitude of the stimulation waveform can becustomized for the patient based on the USL that corresponds to theassociated cochlea stimulation channel. The stimulation waveform canthen be converted into one or more stimulation currents (570), which aredelivered to the cochlea of the patient through the electrode array 24(580).

Prior to stimulating the cochlea of the patient, the components of thecochlear stimulation system 10 must be initialized. FIG. 6 presents aflowchart describing initialization of the cochlear stimulation system10. In an implementation, the speech processor portion 12 can beconfigured to provide power to and detect the presence of an implantablecochlear stimulator 22 (610). Once the implantable cochlear stimulator22 is receiving sufficient operating power from the speech processorportion 12, the implantable cochlear stimulator 22 can execute aself-initialization process (620). The implantable cochlear stimulator22 also can be configured to use one or more items of patient specificinformation stored in the non-volatile memory 420 during theself-initialization process. Additionally, the implantable cochlearstimulator 22 can be configured to perform the self-initializationprocess without reference to any data or other such signals from thespeech processor portion 12. Therefore, the implantable cochlearstimulator 22 is not required to communicate with the speech processorportion 12 before executing the self-initialization process.

The speech processor 18 also can perform a self-initialization process,during which it can using one or more items of non-patient specificinformation stored in the non-volatile memory 28 included in the speechprocessor 18 (630). Further, the speech processor 18 can be configuredto perform the self-initialization process without reference to theinformation stored in the implantable cochlear stimulator 22. In animplementation, the self-initialization process of the implantablecochlear stimulator 22 (620) and the self-initialization process of thespeech processor 18 (630) can be performed simultaneously.

Optionally, the speech processor 18 can transmit one or more items ofcontrol data to the implantable cochlear stimulator 22 in order todefine the status of one or more user controls (640), which can beincluded in the speech processor portion 12 to permit adjustment by thepatient or a specialist. Once the self-initialization processes of theimplantable cochlear stimulator 22 (620) and the speech processor 18(630) have been completed, the speech processor portion 12 can transmitprocessed sound data to the implantable cochlear stimulator 22 in orderto provide stimulation currents to the patient (650). Further, thespeech processor portion 12 can be configured to monitor the presenceand availability of the implantable cochlear stimulator 22 duringoperation, and to continue providing processed sound data as long as theimplantable cochlear stimulator 22 is present (660). In animplementation, the speech processor portion 12 can assess theavailability of the implantable cochlear stimulator periodically, sothat the transfer of sound data is not interrupted.

FIG. 7 describes a method of storing information in a cochlearstimulation system. In a first step, an item of patient specificinformation is determined (710). In a second step, the item of patientspecific information that was determined in the first step istransferred to an implanted portion of the cochlear stimulation system(720). Once the item of patient specific information has beentransferred, a third step is to permanently store the item of patientspecific information in the implanted portion of the cochlearstimulation system (730).

A number of implementations have been disclosed herein. Nevertheless, itwill be understood that various modifications may be made withoutdeparting from the spirit and scope of the claims. Accordingly, otherimplementations are within the scope of the following claims.

The invention claimed is:
 1. A method of performing neurostimulation bya cochlear stimulation system, the method comprising: transferring anitem of patient specific information from a non-implantable speechprocessor of a cochlear stimulation system to an implantableneurostimulator portion of the cochlear stimulation system; storing theitem of patient specific information in a non-volatile memory of theimplantable neurostimulator portion of the cochlear stimulation system;initializing the implantable neurostimulator portion of the cochlearstimulation system using the item of patient specific information storedin the non-volatile memory; and neurostimulating a cochlear nerve withan electrical current configured from the item of patient specificinformation stored in the non-volatile memory, wherein the item ofpatient specific information comprises a personalized configurationsetting of stimulation parameters for use by the implantableneurostimulator portion.
 2. The method of claim 1, wherein the item ofpatient specific information comprises a parameter for use in generatinga stimulation current.
 3. The method of claim 1, wherein thenon-volatile memory of the implantable portion of the cochlearstimulation system is configured to store the item of patient specificinformation in an alterable fashion.
 4. The method of claim 3, furthercomprising: storing an item of non-patient specific information for usein processing a received acoustic signal in a non-volatile memory of anexternal portion of the cochlear stimulation system, wherein theexternal portion is wearable on a head of a patient, and wherein theexternal portion comprises a speech processor.
 5. The method of claim 4,further comprising: storing a substitute item of non-patient specificinformation in the speech processor in place of the item of non-patientspecific information; retaining the item of patient specific informationstored in the non-volatile memory of the implantable portion of thecochlear stimulation system; and generating a stimulation current usingthe substitute item of non-patient specific information and the item ofpatient specific information.
 6. The method of claim 4, furthercomprising: replacing the speech processor with a substitute speechprocessor; retaining the item of patient specific information stored inthe non-volatile memory of the implantable portion of the cochlearstimulation system; and operating the cochlear stimulation system usingthe substitute speech processor.
 7. The method of claim 1, furthercomprising: retrieving the item of patient specific information from thenon-volatile memory of the implantable portion of the cochlearstimulation system.
 8. The method of claim 1, further comprising:associating a write protection with the item of patient specificinformation stored in the non-volatile memory of the implantable portionof the cochlear stimulation system, wherein the write protectionprevents the item of patient specific information from being altered. 9.The method of claim 8, wherein the associated write protection isreversible.
 10. The method of claim 1, further comprising: transferringa substitute item of patient specific information to the implantableportion of the cochlear stimulation system; and storing the substituteitem of patient specific information in the non-volatile memory of theimplantable portion of the cochlear stimulation system in place of theitem of patient specific information.
 11. A cochlear implant system,comprising: an external portion; an implantable portion, communicativelycoupled to the external portion, comprising: an electrode array; anon-volatile storage area; stimulation circuitry, coupled to theelectrode array and the non-volatile storage area, configured forbidirectional communication with the external portion, wherein theexternal portion is wearable on a head of a patient; wherein thestimulation circuitry is configured to receive patient specificinformation from the external portion; store the patient specificinformation in the non-volatile storage area; initialize the stimulationcircuitry using the stored patient specific information withoutreceiving information from the external portion; generate an electricalcurrent by the stimulation circuitry based on the item of patientspecific information; and neurostimulate a cochlear nerve of the patientwith the electrical current.
 12. The cochlear implant system of claim11, wherein the external portion comprises a speech processor.
 13. Thecochlear implant system of claim 12, wherein the speech processor isreplaceable.
 14. The cochlear implant system of claim 11, wherein thepatient specific information comprises a parameter for use by thestimulation circuitry in generating a stimulation current in theelectrode array.
 15. The cochlear implant system of claim 11, whereinthe non-volatile storage area is alterable.
 16. The cochlear implantsystem of claim 11, wherein the stimulation circuitry is furtherconfigured to: receive non-patient specific information from theexternal portion; and store the non-patient specific information in thenon-volatile storage area.
 17. The cochlear implant system of claim 11,wherein the non-volatile storage area provides reversible writeprotection for the patient specific information stored in thenon-volatile storage area, wherein the patient specific informationstored in the non-volatile storage area cannot be altered when writeprotected.
 18. The cochlear implant system of claim 11, whereinstimulation circuitry is further configured to: receive a substituteitem of patient specific information; and store the substitute item ofpatient specific information in place of the patient specificinformation.